Process of preparing filaments, films, and masses from cellulose acetate.



invrrnn sTATEs: PATENT OFFICE.

HARRY s, -1\IOI BK, or BOSTON, MASSACHUSETTS, ASSIGNQR TO CHEMICALrRonUc'rs COMPANY, or BOSTON, MASSACHUSETTS, A CORPORATION 01 MAINE.

' .PROCESS OF PREPARING EILAMENTSIEILMS, AND MAS SE5 FROMCELLULOSEPatented Aug. 11, 1914.

ACETATE.

1 107 222. Specification of Letters Patent.

No Drawing.

To all whom it may concern Be it known that I, HARRY S. MORK, a

citizen of the United States, residing at cellulose acetate, whereby issecured a number'of useful anddesirable advantages, and my process isof. particular value in the production of filaments for artificial silk.

Cellulose acetate is soluble in many different solvents and solventmixtures, among which may be mentioned tetrachlorethane otherwise knownas acetylene tetrachlorid, and mixtures of acetylene tctrachlorid withmethyl or ethyl alcohol, as described in Letters Patent $51,009,116, dted November 21, 191-1, and #1,035,108 dat August 6, 1912, to W. H.Walker.

On'account of its great solvent power and its neutral character,acetylene tetrachlorid, but better acetylene tetrachlorid' mixed with analcohol, is a highly desirable solvent for cellulose acetate generally,but especially in the preparation of solutions of cellulose a-cetate forspinning into artificial silk, where a powerful solvent is essential tocompensate for slight variations in the manufacture of the celluloseacetate to be dissolved, thereby enabling the production of spinningsolu tions or practically perfect homogeneity and uniform viscosity.Acetylene tetrachlorid is moreover absolutely non-inflammable and itsVapors are likewisenon-inflammable, and it imparts this valuableproperty to a more or less degree to other liquids with which it may bemixed, this degree, of course, depending on the boiling point andinflammability of these liquids.

Solutions of cellulose acetate in acetylene tet-rachlorid with or.without the addition of an alcohol or other diluents miscible with'itmay be forced under pressure through spinnerets into a number of liquidswhich will coagulate the cellulose acetate so that it may be drawn outinto threads which when dry constitute cellulose acetate artificial silkor monofil. Among such available coagulation liquids may be mentionedthe lower aliphatic alcohols, as methyl and ethyl alcohol, the coal tarhydrocarbons such as benzol, toluol,

Application filed March 27,1914. I Serial No. 827,750.

etc., and the petroleum hydrocarbons, such as gasolene, kerosene, etc.Now, I have found that these different coagulating liqllldS perform thisfunction in different ways and the silks produced thereby have differentphysical properties, and I have further fpund that the petroleumhydrocarbons, part cularly the kerosenes, when used as a settlng bathfor cellulose acetate solutions in acetylene tetrachlo-rid as theessential solvent, possess certain advantages which make my process adesirable and novel one. For reasons of economic recovery of theacetylene tetrachlorid from the coagulating bath, it is desirable thoughnot essential to select a kerosene, the boiling point range of which issufficiently high that the acetylene 'tetrachlo-rid can be readilyseparated from it by fractional distillation as the major constituentsof the lower boiling fractions, and the boiling point range of which issufiiciently narrow so that there shall not be much oily residueremaining in ,the silk. The selection of kerosene of this type is alsoadvantageous because it will be safe to use on account of its high flashpoint, and when mlxed with acetylene tetrachlorid in suitableproportions the mixture will be absolutely non-inflammable. Such acondition exists on the spools on which the original spun threads arewound, and can be made to exist in the coagulation bath, which I havefound it advantageous to prepare, by mixing acetylene tetrachlorid withthe kerosene, and maintaining the balance between the two by theaddition of kerosene to take care of the acetylene tetrachlorid whichaccumulates in the bath from the cellulose acetate solution forced intoit. But I have furthermore found that kerosene, orpreferably, as statedabove, a mixture of kerosene and acetylene tetrachlorid, into whichmixture of course the kerosene must be converted as soon as the spinningsolution is forced into it, posdry Weight of the silk, and thecoagulated silk on the spools will be very bulky, and in drying will besubject to a large shrinkage. Also on account of the low boiling pointsof the alcohols, these will leave the silk largely before the acetylenetetrachlorid, and the dry silk becomes harsh on this account. Muchthesame effect of retention of setting bath and solvent with consequentbulkiness of the coagulated thread occurs if the coal tar hydrocarbonsare used as a setting or coagulating bath, although the harshness of thesilk can be largely overcome by the selection of a coal tar hydrocarbonof sufficiently' high boiling point. With kerosene, however, as theessential constituent of the coagulating bath, the coagulation is muchmore intense as measured by the amount of solvent and setting bathremaining in the silk on the spools after centrifuging ofi the looselyclinging excess, for the thread will hold back not much more thanapproximately its own weight of solvent and setting liquid and sometimeseven less than this amount. Holding back such a relatively small amountof liquid the coagulated thread is less bulky and a great deal more ofit can be wound on the spools, the thread is not subject to so muchshrinkage in drying, weaves and knits better, and is much more soft intexture and feel.

It is not essential for the proper and successful conduct of my processthat the cellu-' lose acetate solution be of a definite composition, i.e. the amount of cellulose acetate dissolved may vary, depending on theviscosity of its solutions, the pressure available for forcing thesolution through the spinning orifices, the rate of spinning, etc, andthe solvent may be variable, although it is necessary that acetylenetetrachlorid shall constitute the major component of the solvent.Likewise it is not necessary to have a setting or coagulating bath ofdefinite composition, i. e. the petroleum hydrocarbons may vary ingravity and boiling point, as long as they meet the other requirementsof the invention, and the proportion of acety lene tetraehlorid may varyWithin wide limits and still make the bath a suitable coagulent. Also itmay be desirable to color the coagulating bath as a means of impartingcolor ,to the silk, or add small percentages of oils or to add othersuitable materials to the bath for the purpose of imparting greatersoftness to the silk.

.While my invention has been described particularly for the productionof artificial silk,.yet the principles involved are the same whetherproducing filaments so fine as to classify them as artificial silk, orby enlargement of the orifices may be of such a size as to form monofil,or horsehair or other animal hair substitute, or by shaping the orificesmay cause the production of bands or films; and furthermore, thesolution may be brought in contact with the setting bath in any suitablemanner so as to coagulate it into a filament, film, or mass.

I claim 1. That improvement in the art of pre paring filaments, filmsand masses of cellulose acetate which consists in dissolving celluloseacetate in a solvent composed largely of acetylene tetrachlorid and thencoagulating the same by a mixture of an aliphatic hydrocarbon andacetylene tetrachlorid, the boiling point of the hydrocarbon beinghigher than the boiling point of acetylene tetrachlorid.

2. That improvement in the art of pre paring filaments, films and massesof cellulose acetate which consists in dissolving cellulose acetate in asolvent composed largely of acetylene tetrachlorid and then coagulatingthe same by a mixture of a petroleum hydrocarbon and acetylenetetrachlorid, the boiling point of the petroleum hydrocarbon beinghigher than the boiling point of acetylene tetrachlorid.

3. That improvement in the art of preparing filaments, films and massesof cellulose acetate which consists in dissolving cellulose acetate in asolvent composed largely of acetylene tetrachlorid and then coagulatingthe same by a mixture of aliphatic hydrocarbons with acetylenetetrachlorid, the average boiling point of the aliphatic hydrocarbonsbeing higher than the boiling point of acetylene tetrachlorid.

4:. That improvement in the art of prepering filaments, films and massesof cellulose acetate which consists in dissolving cellulose acetate in asolvent composed largely of acetylene tetrachlorid and then coagulatingthe same by a mixture of petroleum hydrocarbons with acetylenetet-rachlorid, the average boiling point of the petroleum hydrocarbonsbeing higher than the boiling point of acetylene tetrachlorid.

5. That improvement in the art of pre paring filaments, films-and massesof cellulose acetate which consists in dissolving cellulose acetate in asolvent composed largely of acetylene tetrachlorid and then coagulatingthe same by a mixture of a kerosene and acetylene tetrachlorid.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

HARRY S. MORK. Witnesses:

B. J. NOYES, H. B. DAVIS.

